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<p>Dart&#x8BED;&#x8A00;&#x4E2D;&#x7684;&#x8FD0;&#x7B97;&#x7B26;&#x4E0E;Java&#x4E2D;&#x7684;&#x7EDD;&#x5927;&#x591A;&#x6570;&#x76F8;&#x540C;&#x3002;</p>
<h3 id="&#x7B97;&#x672F;&#x8FD0;&#x7B97;&#x7B26;"><a name="&#x7B97;&#x672F;&#x8FD0;&#x7B97;&#x7B26;" class="anchor-navigation-ex-anchor" href="#&#x7B97;&#x672F;&#x8FD0;&#x7B97;&#x7B26;"><i class="fa fa-link" aria-hidden="true"></i></a>&#x7B97;&#x672F;&#x8FD0;&#x7B97;&#x7B26;</h3>
<p><code>+</code>&#x3001;<code>-</code>&#x3001;<code>*</code>&#x3001;<code>/</code>&#x3001;<code>%</code>&#x540C;Java&#x8BED;&#x8A00;</p>
<p>Dart&#x4E2D;&#x53C8;&#x591A;&#x51FA;&#x4E86;&#x4E00;&#x4E2A;&#x6574;&#x9664;&#x8FD0;&#x7B97;&#x7B26;<code>~/</code>&#xFF0C;&#x4E0E;&#x666E;&#x901A;&#x9664;&#x53F7;&#x7684;&#x533A;&#x522B;&#x662F;&#x5C06;&#x76F8;&#x9664;&#x540E;&#x7684;&#x7ED3;&#x679C;&#x53D6;&#x6574;&#x8FD4;&#x56DE;&#x3002;</p>
<h3 id="&#x7C7B;&#x578B;&#x5224;&#x5B9A;&#x8FD0;&#x7B97;&#x7B26;"><a name="&#x7C7B;&#x578B;&#x5224;&#x5B9A;&#x8FD0;&#x7B97;&#x7B26;" class="anchor-navigation-ex-anchor" href="#&#x7C7B;&#x578B;&#x5224;&#x5B9A;&#x8FD0;&#x7B97;&#x7B26;"><i class="fa fa-link" aria-hidden="true"></i></a>&#x7C7B;&#x578B;&#x5224;&#x5B9A;&#x8FD0;&#x7B97;&#x7B26;</h3>
<p>&#x4EE5;&#x4E0B;&#x662F;Dart&#x589E;&#x52A0;&#x7684;&#x7C7B;&#x578B;&#x76F8;&#x5173;&#x7684;&#x8FD0;&#x7B97;&#x7B26;&#x3002;</p>
<table>
<thead>
<tr>
<th>&#x64CD;&#x4F5C;&#x7B26;</th>
<th>&#x89E3;&#x91CA;</th>
</tr>
</thead>
<tbody>
<tr>
<td><code>as</code></td>
<td>&#x7528;&#x4E8E;&#x7C7B;&#x578B;&#x8F6C;&#x6362;</td>
</tr>
<tr>
<td><code>is</code></td>
<td>&#x5982;&#x679C;&#x5BF9;&#x8C61;&#x662F;&#x6307;&#x5B9A;&#x7684;&#x7C7B;&#x578B;&#x5C31;&#x8FD4;&#x56DE; True</td>
</tr>
<tr>
<td><code>is!</code></td>
<td>&#x5982;&#x679C;&#x5BF9;&#x8C61;&#x4E0D;&#x662F;&#x6307;&#x5B9A;&#x7684;&#x7C7B;&#x578B;&#x8FD4;&#x56DE; True</td>
</tr>
</tbody>
</table>
<p>&#x5F53; <code>obj</code> &#x5B9E;&#x73B0;&#x4E86; <code>T</code> &#x7684;&#x63A5;&#x53E3;&#x65F6;&#xFF0C; <code>obj is T</code> &#x624D;&#x662F; true&#x3002;&#x7C7B;&#x4F3C;&#x4E8E;Java&#x4E2D;&#x7684;<code>instanceof</code>&#x3002;</p>
<p>Dart&#x4E2D;&#x4F7F;&#x7528; <code>as</code> &#x64CD;&#x4F5C;&#x7B26;&#x628A;&#x5BF9;&#x8C61;&#x8F6C;&#x6362;&#x4E3A;&#x7279;&#x5B9A;&#x7684;&#x7C7B;&#x578B;&#xFF0C;&#x5982;&#x65E0;&#x6CD5;&#x8F6C;&#x6362;&#x5219;&#x4F1A;&#x629B;&#x51FA;&#x5F02;&#x5E38;&#xFF0C;&#x56E0;&#x6B64;&#x5728;&#x8F6C;&#x6362;&#x524D;&#x6700;&#x597D;&#x4F7F;&#x7528;<code>is</code>&#x8FD0;&#x7B97;&#x7B26;&#x8FDB;&#x884C;&#x68C0;&#x6D4B;&#x3002;</p>
<pre><code class="lang-dart"><span class="hljs-comment">// &#x5C06;p&#x8F6C;&#x6362;&#x4E3A;Person&#x7C7B;&#x578B;&#x518D;&#x64CD;&#x4F5C;</span>
(p <span class="hljs-keyword">as</span> Person).name = <span class="hljs-string">&apos;Bruce&apos;</span>;
</code></pre>
<h3 id="&#x6761;&#x4EF6;&#x8868;&#x8FBE;&#x5F0F;"><a name="&#x6761;&#x4EF6;&#x8868;&#x8FBE;&#x5F0F;" class="anchor-navigation-ex-anchor" href="#&#x6761;&#x4EF6;&#x8868;&#x8FBE;&#x5F0F;"><i class="fa fa-link" aria-hidden="true"></i></a>&#x6761;&#x4EF6;&#x8868;&#x8FBE;&#x5F0F;</h3>
<p>Dart&#x4E2D;&#x4E5F;&#x652F;&#x6301;&#x4E09;&#x76EE;&#x8868;&#x8FBE;&#x5F0F;
<code>condition ? expr1 : expr2</code></p>
<p>&#x9664;&#x6B64;&#x5916;&#xFF0C;Dart&#x8FD8;&#x589E;&#x52A0;&#x4E86;&#x975E;&#x7A7A;&#x6761;&#x4EF6;&#x5224;&#x65AD;&#x7B26;<code>??</code>
<code>expr1 ?? expr2</code>
&#x4E0A;&#x8FF0;&#x8FD0;&#x7B97;&#x8868;&#x793A;&#xFF0C;&#x5982;&#x679C;expr1&#x7684;&#x503C;&#x4E0D;&#x7B49;&#x4E8E;<code>null</code>&#xFF0C;&#x5219;&#x8FD4;&#x56DE;&#x5176;&#x503C;&#xFF1B; &#x5426;&#x5219;&#x6267;&#x884C;&#x8868;&#x8FBE;&#x5F0F;expr2&#x5E76;&#x8FD4;&#x56DE;&#x5176;&#x7ED3;&#x679C;&#x3002;</p>
<pre><code class="lang-dart"><span class="hljs-keyword">var</span> str1 =  <span class="hljs-string">&quot;Hello&quot;</span>;
<span class="hljs-keyword">var</span> str2 =  <span class="hljs-string">&quot;world&quot;</span>;
<span class="hljs-keyword">var</span> result = str1 ?? str2.toUpperCase();
</code></pre>
<h3 id="&#x7EA7;&#x8054;&#x8FD0;&#x7B97;&#x7B26;"><a name="&#x7EA7;&#x8054;&#x8FD0;&#x7B97;&#x7B26;" class="anchor-navigation-ex-anchor" href="#&#x7EA7;&#x8054;&#x8FD0;&#x7B97;&#x7B26;"><i class="fa fa-link" aria-hidden="true"></i></a>&#x7EA7;&#x8054;&#x8FD0;&#x7B97;&#x7B26;</h3>
<blockquote>
<p>&#x6211;&#x4EEC;&#x901A;&#x5E38;&#x4F7F;&#x7528;<code>.</code>&#x64CD;&#x4F5C;&#x7B26;&#x8C03;&#x7528;&#x5BF9;&#x8C61;&#x7684;&#x65B9;&#x6CD5;&#xFF0C;&#x8FD9;&#x5728;Dart&#x4E2D;&#x4E5F;&#x662F;&#x652F;&#x6301;&#x7684;&#xFF0C;&#x4F46;&#x662F;Dart&#x53E6;&#x5916;&#x589E;&#x52A0;&#x4E86;&#x4E00;&#x79CD;&#x7EA7;&#x8054;&#x8FD0;&#x7B97;&#x7B26;<code>..</code>&#xFF0C;&#x7528;&#x4E24;&#x4E2A;&#x70B9;&#x8868;&#x793A;&#x3002;</p>
</blockquote>
<p><code>&#x7EA7;&#x8054;&#x8FD0;&#x7B97;&#x7B26;</code>&#x53EF;&#x4EE5;&#x5728;&#x540C;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#x4E0A;&#x8FDE;&#x7EED;&#x8C03;&#x7528;&#x591A;&#x4E2A;&#x65B9;&#x6CD5;&#x4EE5;&#x53CA;&#x8BBF;&#x95EE;&#x6210;&#x5458;&#x53D8;&#x91CF;&#x3002; &#x4F7F;&#x7528;&#x5B83;&#x53EF;&#x4EE5;&#x907F;&#x514D;&#x521B;&#x5EFA;&#x4E34;&#x65F6;&#x53D8;&#x91CF;&#xFF0C; &#x5199;&#x51FA;&#x66F4;&#x6D41;&#x7545;&#x7684;&#x4EE3;&#x7801;&#x3002;</p>
<p>&#x5047;&#x5982;&#x7C7B;Person&#x6709;&#x4E09;&#x4E2A;&#x65B9;&#x6CD5;&#xFF0C;<code>setName</code>&#x3001;<code>setAge</code>&#x3001;<code>save</code>&#xFF0C;&#x5219;&#x53EF;&#x5982;&#x4E0B;&#x8C03;&#x7528;</p>
<pre><code class="lang-dart"><span class="hljs-keyword">new</span> Person()..setName(<span class="hljs-string">&quot;Bob&quot;</span>)..setAge(<span class="hljs-number">20</span>)..save();
</code></pre>
<p>&#x4F7F;&#x7528;<code>&#x7EA7;&#x8054;&#x8FD0;&#x7B97;&#x7B26;</code>&#x8C03;&#x7528;&#x65B9;&#x6CD5;&#xFF0C;&#x65E0;&#x9700;&#x8BE5;&#x65B9;&#x6CD5;&#x8FD4;&#x56DE;&#x5BF9;&#x8C61;&#x672C;&#x8EAB;&#x5373;&#x53EF;&#x8FDE;&#x7EED;&#x7684;&#x6D41;&#x5F0F;&#x7684;&#x8C03;&#x7528;&#x8BE5;&#x5BF9;&#x8C61;&#x7684;&#x5176;&#x4ED6;&#x65B9;&#x6CD5;&#x3002;</p>
<h3 id="&#x6761;&#x4EF6;&#x6210;&#x5458;&#x8BBF;&#x95EE;&#x7B26;"><a name="&#x6761;&#x4EF6;&#x6210;&#x5458;&#x8BBF;&#x95EE;&#x7B26;" class="anchor-navigation-ex-anchor" href="#&#x6761;&#x4EF6;&#x6210;&#x5458;&#x8BBF;&#x95EE;&#x7B26;"><i class="fa fa-link" aria-hidden="true"></i></a>&#x6761;&#x4EF6;&#x6210;&#x5458;&#x8BBF;&#x95EE;&#x7B26;</h3>
<blockquote>
<p>&#x5728;Java&#x4E2D;&#x5F88;&#x5BB9;&#x6613;&#x78B0;&#x5230;&#x607C;&#x4EBA;&#x7684;&#x7A7A;&#x6307;&#x9488;&#x9519;&#x8BEF;&#xFF0C;&#x56E0;&#x6B64;&#x5728;&#x65B9;&#x6CD5;&#x8C03;&#x7528;&#x524D;&#x9700;&#x8981;&#x8FDB;&#x884C;&#x5BF9;&#x8C61;&#x7684;&#x975E;&#x7A7A;&#x5224;&#x65AD;&#xFF0C;&#x8FD9;&#x6837;&#x7684;&#x5224;&#x65AD;&#x8BED;&#x53E5;&#x4F7F;&#x4EE3;&#x7801;&#x53D8;&#x5F97;&#x5197;&#x957F;&#xFF0C;&#x53EF;&#x8BFB;&#x6027;&#x5DEE;&#xFF0C;&#x4E0D;&#x6574;&#x6D01;&#x3002;Dart&#x4E2D;&#x5219;&#x53D1;&#x660E;&#x4E86;&#x4E00;&#x4E2A;&#x65B0;&#x7684;&#x8FD0;&#x7B97;&#x7B26;&#x7528;&#x4E8E;&#x5904;&#x7406;&#x6B64;&#x7C7B;&#x60C5;&#x51B5;&#x3002;</p>
</blockquote>
<p>&#x6761;&#x4EF6;&#x6210;&#x5458;&#x8BBF;&#x95EE;&#x7B26;<code>?.</code>&#xFF0C;&#x5B83;&#x548C;<code>.</code>&#x7C7B;&#x4F3C;&#xFF0C;&#x4F46;&#x662F;&#x8FD0;&#x7B97;&#x7B26;&#x5DE6;&#x8FB9;&#x7684;&#x5BF9;&#x8C61;&#x4E0D;&#x80FD;&#x4E3A;<code>null</code>&#xFF0C;&#x5426;&#x5219;&#x8FD4;&#x56DE;<code>null</code>&#xFF0C;&#x82E5;&#x5BF9;&#x8C61;&#x4E0D;&#x4E3A;<code>null</code>&#xFF0C;&#x5219;&#x8FD4;&#x56DE;&#x5BF9;&#x8C61;&#x672C;&#x8EAB;&#x3002;</p>
<pre><code class="lang-dart"><span class="hljs-comment">// list1&#x9ED8;&#x8BA4;&#x503C;&#x4E3A;null</span>
<span class="hljs-built_in">List</span> list1;
<span class="hljs-built_in">print</span>(list1?.length);  <span class="hljs-comment">// null</span>

<span class="hljs-built_in">List</span> list2 = [];
<span class="hljs-built_in">print</span>(list2?.length);  <span class="hljs-comment">// 0</span>
</code></pre>
<hr>
<p><strong>&#x516C;&#x4F17;&#x53F7;&#x201C;&#x7F16;&#x7A0B;&#x4E4B;&#x8DEF;&#x4ECE;0&#x5230;1&#x201D;</strong></p>
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